Promotion Rules

Return the ndarray data type with the smallest size and closest "kind" to which ndarray data types can be safely cast.

Installation

npm install @stdlib/ndarray-promotion-rules

Usage

var promotionRules = require( '@stdlib/ndarray-promotion-rules' );

promotionRules( [dtype1, dtype2] )

If provided data types, returns the ndarray data type with the smallest size and closest "kind" to which ndarray data types can be safely cast.

var out = promotionRules( 'float32', 'uint32' );
// returns 'float64'

If a data type to which data types can be safely cast does not exist (or is not supported), the function returns -1.

var out = promotionRules( 'binary', 'generic' );
// returns -1

If not provided data types, the function returns a promotion table.

var out = promotionRules();
// returns {...}

var f32 = out[ 'float32' ];
// returns {...}

var rule = f32[ 'uint32' ];
// returns 'float64'

If provided an unrecognized or unsupported dtype, the function returns null.

var out = promotionRules( 'foo', 'generic' );
// returns null

Examples

var dtypes = require( '@stdlib/ndarray-dtypes' );
var promotionRules = require( '@stdlib/ndarray-promotion-rules' );

var DTYPES;
var dt1;
var dt2;
var dt;
var i;
var j;

// Get the list of supported ndarray data types:
DTYPES = dtypes();

// Print the promotion rule for each pair of ndarray data types...
for ( i = 0; i < DTYPES.length; i++ ) {
    dt1 = DTYPES[ i ];
    for ( j = 0; j < DTYPES.length; j++ ) {
        dt2 = DTYPES[ j ];
        dt = promotionRules( dt1, dt2 );
        console.log( '(%s, %s) => %s', dt1, dt2, dt );
    }
}

See Also

• @stdlib/ndarray-casting-modes: list of ndarray casting modes.
• @stdlib/ndarray-dtypes: list of ndarray data types.
• @stdlib/ndarray-safe-casts: return a list of ndarray data types to which a provided ndarray data type can be safely cast.

Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.

Community

License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.